Electronic musical instrument

ABSTRACT

In an electronic musical instrument of the waveshape memory type including at least one waveshape memory for storing and reproducing sample values of a musical sound wave to be generated, the waveshape memory stores the sample values of the complete waveshape of a musical tone with a shaped envelope.

This is a continuation of application Ser. No. 507,948 filed June 24, 1983, which is a continuation of Ser. No. 303,174, filed Sept. 17, 1981, now abandoned, which is a continuation of Ser. No. 064,917, filed Aug. 8, 1979, now U.S. Pat. No. 4,383,462, which is a continuation of Ser. No. 784,941, filed Apr. 5, 1977, now abandoned.

BACKGROUND OF THE INVENTION

(a) Field of the invention:

The present invention relates to an electronic musical instrument, and more particularly pertains to an electronic musical instrument capable of simulating natural sounds using a waveshape memory system.

(b) Description of the prior art:

Heretofore, many attempts have been made to electronically or electrically reproduce, by electronic musical instruments, natural sounds existing in the natural world and to produce arbitrary artificial sounds. For example, according to one propsed method, original sounds are recorded on magnetic tapes or the like and the recorded sound information is reproduced by mechanically driving the magnetic tapes selectively upon depressions of keys in an electronic musical instrument. Such method, therefore, is not purely electronic. Accordingly, it is difficult to quickly and faithfully follow up depressions of keys when they are performed at a high speed. Furthermore, in such a case, the rise and fall of a produced musical sound become very unnatural due to the mechanical nature of the tape feed.

There are many problems which are encountered in electronically synthesizing natural sounds. Generally speaking, a natural sound is formed of an extremely complicated combination of such factors as amplitude, frequency and phase. Moreover, all these factors vary with time. Therefore, it has been practically impossible to satisfy all such conditions, i.e. it has not been possible to reproduce all the complicated variations. Thus, the attempts to simulate natural sounds existing in the natural world have not succeeded in practice.

SUMMARY OF THE INVENTION

The present invention has been worked out in view of the circumstances described above, and an object thereof is to provide an electronic musical instrument capable of perfectly simulating natural sounds existing in the natural world and further capable of generating a variety of artificial sounds as musical sounds.

In order to accomplish this object according to the present invention, the electronic musical instrument comprises a waveshape memory system, and the information of the complete waveshape ranging from the attack to the decay of each musical sound to be produced is preliminarily stored in the waveshape memory. The output of the waveshape memory is directly utilized as a musical sound signal. Furthermore, according to the present invention, a plurality of such waveshape memories are used. At least one of such waveshape memories stores the information of part of the complete waveshape ranging from the attack to the decay of each musical sound to be produced, and another waveshape memory or memories store information of all or part of the remainder of the complete waveshape, and these waveshape memories are successively and/or repeatedly read out.

Here, the term "waveshape memory system" refers to a system for storing sample values of a waveshape of a musical sound to be produced and for reading out these sample values at a selected speed (such system is stated in for example, U.S. Pat. No. 3,515,792). In the prior art waveshape memory, however, the waveshape memory system stores the waveshape of a standard sound in one period without its envelope information added. The envelope shaping is performed by separately generating the envelope information and multiplying it with the waveshape signals which are repeatedly read out from the memory.

In this specification, the term "complete waveshape" of a musical sound refers to a tone waveshape which is afforded with an envelope shaping, whereas the term "tone waveshape" refers to a tone waveshape without the envelope shaping. That is, according to the present invention, a waveshape memory stores the "complete" waveshape of the whole or a part of the whole one musical tone. For saving the number of bits of the memory means, it is preferable to store the "complete" waveshape for only a part of a musical tone. From this point of view, the "complete" waveshape in the attacking period of a musical tone may be stored in a memory and the waveshape of the remainder period of the musical tone may be formed by repeatedly reading out a standard waveshape from another memory which has independently memorized the standard waveshape and multiplying the signal repeatedly read out from said another memory by a sustaining envelope and/or a decaying envelope to constitute the above-said complete waveshape for the remaining period. Such arrangement is particularly suitable for generating percussive tones such as the sounds of a piano.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a keyboard device to be used in the embodiments of the present invention.

FIGS. 2a to 2f show waveshapes at various outputs of the device of FIG. 1.

FIG. 3 is a block diagram of an electronic musical instrument according to the first embodiment of the present invention.

FIGS. 4 and 5 are block diagrams of an addresser and a self-holding flip-flop loop for elucidating the essential portions of the embodiments of FIG. 3.

FIGS. 6, 7 and 8 are block diagrams of an electronic musical instrument according to the second, third and fourth embodiments of the present invention, respectively.

FIG. 9 is a block diagram of an electronic musical instrument according to a modified embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the embodiments to be described hereinbelow, similar keyboard devices are used. Therefore, description will be first made with respect to the keyboard device.

FIG. 1 shows a keyboard circuit for an individual key. Similar circuits are also provided for other keys of the keyboard. In the figure, a key switch KSW switches the power supply from a voltage source E to a circuit for generating various key operation signals. A differentiation circuit is formed with resistors R₀ and R₁ and a capacitor C₁. Another differentiation circuit is formed with a capacitor C₂ and a resistor R₂. Diodes D₁ and D₂ are used for blocking pulses of negative polarity. Inverters INV₁ to INV₄ invert the polarity of the input signals.

A point A is grounded through the resistor R₀ and connected to the voltage source E through the key switch KSW. The voltage from the voltage source E appears at point A during the key is depressed. Thus, a key depression signal A is generated upon depression of a key as shown in FIG. 2a. The inverter INV₄ forms an inverted or complimentary key depression signal A as shown in FIG. 2b. The key depression signal A is differentiated by the differentiation circuit formed with the resistors R₀ and R₁ and the capacitor C₁ to generate a positive and a negative pulse at the times of key depression and key release. The negative pulse signal corresponding to the key release is blocked by the diode D₁. Thus, the diode D₁ supplies only the key depression pulse signal KD as shown in FIG. 2c. The inverter INV₁ inverts the polarity of this key depression pulse to generate an inverted or complimentary key depression pulse KD as shown in FIG. 2d. Further, the key depression signal A is inverted through the inverter INV₂ and then differentiated by the differentiation circuit formed of the capacitor C₂ and the resistor R₂ to generate a negative and positive pulse signal at the times of key depression and key release. The negative pulse corresponding to the key depression is blocked by the diode D₂. Thus, the diode D₂ provides the key release pulse signal KR as shown in FIG. 2e. The inventor INV₃ inverts the polarity of this key release pulse to generate the inverted or complimentary key release pulse signal KR as shown in FIG. 2f. In this way, the keyboard device provides a group of signals upon each key operation.

Description will hereinbelow be made with respect to the embodiments of the present invention. Throughout these embodiments, the circuit shown in the figure represents that for a single key. Similar circuit structure may be adopted for each key in the keyboard or in a part of the keyboard.

Embodiment 1

FIG. 3 shows the first embodiment of the electronic musical instrument adapted for providing percussive tones. In this embodiment, the "complete" waveshape for a whole one musical tone is stored in and read out from a memory, which may provide all the attack, sustain and decay envelopes when the key is depressed and kept depressed. Another memory is provided for damping the musical tone upon release of the key while not depressing the damper pedal.

The waveshape memories WM₃₁ and WM₃₂ are respectively addressed by addressers AD₃₁ and AD₃₂. The first waveshape memory WM₃₁ stores therein the complete waveshape from the attack to the decay of a tone (curve a), while the second waveshape memory WM₃₂ stores a damping envelope waveshape (curve b). Therefore, when the read-out of the second waveshape memory WM₃₂ is initiated, for example by the release of the key while reading out the first waveshape memory WM₃₁, waveshape signals which are read out from the respective waveshape memories WM₃₁ and WM₃₂ are multiplied in a multiplier unit MU₃₀ to provide a resultant waveshape of which the decay becomes faster from the time of the key release as shown by curve c. Accordingly, when the percussive tone of a sound of a piano or the like is stored in the first waveshape memory WM₃₁ and a suitable decay envelope waveshape in the second waveshape memory WM₃₂, a very excellent simulation of the percussive tone is obtained. Here, the memory contents in the two waveshape memories WM₃₁ and WM₃₂ may be arbitrarily altered in conformity with the nature of an intended sound.

Now, the details of the arrangement of FIG. 3 will be described along with the operation thereof.

When a key depression pulse KD as shown in FIG. 2c is generated by a key depressing operation as described in connection with FIG. 1, a flip-flop FF₃₁ is set to continuously generate a Q output. Then, clock pulses of a predetermined frequency are directly transmitted through an AND circuit AND₃₁ to the addresser AD₃₁, which sequentially generate a pulse at their each output, one at a time, to thereby address the waveshape memory WM₃₁ to read out the waveshape which is stored therein. When the addresser AD₃₁ generates the last bit output, the flip-flop FF₃₁ is re-set, and the reading-out of the waveshape memory WM₃₁ terminates.

An example of the addresser AD₃₁ is shown in FIG. 4, which comprises a counter 41 and a decoder 42. The content of the addresser AD₃₁, i.e. the content of the counter 41, is cleared by the key depression pulse KD before the initiation of counting. Other addressers referred to in this specification may have similar structures. The waveshape memory WM₃₁ may be formed with a ROM or the like. Other waveshape memories referred to in this specification may have similar structures.

Now, let us assume that the key releasing operation is conducted while the first waveshape memory WM₃₁ is being read out and that a damper pedal is released and an associated damper switch DP is closed for effecting an abrupt decay of the sound. When the damper switch DP is open, a voltage +V is applied to an inverter INV₃₁ through a resistance R₃₀. When the damper switch DP is closed, the ground (zero) potential 0 is applied to the inverter INV₃₁ and accordingly the output of the inverter INV₃₁ becomes "1". Upon the key release with the damper switch DP closed, a key release pulse KR as shown in FIG. 2e is applied to and allowed to transmit through an AND circuit AND₃₂ and an OR circuit OR₃₁ to a D-type flip-flop FF₃₂. Thus, flip-flop FF₃₂ provides a Q output. The Q output is delivered to AND circuit AND₃₃ and AND₃₄. The inverted key depression pulse KD which is applied to the AND circuit AND₃₃ is "1" when the key has been released. Furthermore, the output of an inverter INV₃₂ which is applied with the final bit output of the addresser AD₃₂ is also applied to the AND circuit AND₃₃ and is "1" since there is yet not output at the final bit of the addresser AD₃₂. Accordingly, the AND circuit AND₃₃ satisfies the AND condition and feeds the Q output of the flip-flop FF₃₂ back to the input of the same flip-flop FF₃₂ through the OR circuit OR₃₁. Therefore, the flip-flop FF₃₂ is self-held.

The self-held flip-flop FF₃₂ permits the clock pulses φ of the predetermined frequency to pass through an AND circuit AND₃₄ to enter into the addresser AD₃₂. The addresser AD₃₂ addresses the waveshape memory WM₃₂ storing the decaying envelope to read out the sample values of the memory content. Here, when an output is generated at the final bit of the addresser AD₃₂, the output of the inverter INV₃₂ becomes "0" and the AND condition for the AND circuit AND₃₃ is destroyed. Therefore, the self-holding of the flip-flop FF₃₂ is released, and the drive of the addresser is terminated. In order to prepare for the key release and a re-depression of the key, the addresser AD₃₂ has its content cleared by either of the key depression pulse KD and the key release pulse KR through the OR circuit OR₃₂.

In the manner described above, according to this embodiment, a rapidly decaying envelope is given on the waveshape which is read out from the first waveshape memory WM₃₁, i.e. multiplied in the multiplier unit MU₃₀ by the closure of the damper switch DP and the key release. Thus, the so-called damper effect is afforded by which the volume of the sound decreases quickly after the release of the key.

FIG. 5 shows a self-holding flip-flop circuit in which an output of a D-type flip-flop FF₅₀ can be self-held by a loop including an OR circuit OR₅₀ and an AND circuit AND₅₀ in the manner as described above. Since such self-holding circuit will also be used in the ensuing embodiments, detailed explanation thereof will be omitted.

Embodiment 2

FIG. 6 shows a second embodiment of the present invention, in which the "complete" waveshape is stored in a memory only for the attacking period of a musical tone. Although the embodiment is suitable to obtain a percussive tone similar to the first embodiment, the use thereof is not restricted to the generation of such percussive tones.

This embodiment uses three kinds of waveshape memories WM₆₁, WM₆₂ and WM₆₃ which are respectively addressed by addressers AD₆₁, AD₆₂ and AD₆₃. The first waveshape memory WM₆₁ stores therein the complete waveshape in the attack period, the second waveshape memory WM₆₂ stores at least one fundamental period of a musical tone waveshape, and the third waveshape memory WM₆₃ stores an envelope waveshape ranging from the sustain to the decay, which envelope shape follows the attack. Therefore, when the envelope shaping is performed while reading out the second waveshape memory WM₆₂ following the reading-out of the first waveshape memory WM₆₁, the musical sound having similar effects as those of the first embodiment can be produced using simpler memories than those in the first embodiment. Here, the memory content of the third waveshape memory WM₆₃ may not include the sustain envelope.

Now, the construction and the operation of this embodiment will be made apparent through the following description of the processes of forming a musical sound.

The arrangement of a flip-flop FF₆₁, and AND circuit AND₆₁ and the addresser AD₆₁ for addressing sampling values in The waveshape memory WM₆₁ upon arrival of a key depression pulse KD is similar to the arrangement for addressing the first waveshape memory WM₃₁ in the first embodiment. Thus, the description thereof is omitted here. When the reading-out of the first waveshape memory WM₆₁ which stores the complete waveshape of the attack period terminates and the final bit output of the addresser AD₆₁ is generated, this final bit output signal re-sets the flip-flop FF₆₁. The final bit output is also utilized as a signal 1MF for driving the addressers AD₆₂ and AD₆₃ which address the second and third waveshape memories WM₆₂ and WM₆₃.

A D-type flip-flop FF₆₂ is set through an OR circuit OR₆₁ by the signal 1MF. The output of the flip-flop FF₆₂ is self-held when the AND condition of an AND circuit AND₆₂ is satisfied. The flip-flop FF₆₂ supplies clock pulses of a predetermined frequency to the addresser AD₆₂ through an AND circuit AND₆₃. Thus, the addresser AD₆₂ is driven to read out the content of the waveshape memory WM₆₂. The AND condition for the AND circuit AND₆₂ for generating an output "1" is that the inverted key depression signal KD is "1" and also the inverted output DF (inverted by an inverter INV₆₂) of the final bit output DF of the addresser AD₆₃ assigned for addressing the third waveshape memory WM₆₃ is "1". Therefore, unless the reading-out of the third waveshape memory WM₆₃ has terminated after the depression of the key, the AND condition of the AND circuit AND₆₂ holds, and the flip-flop FF₆₂ self-holds.

A D-type flip-flop FF₆₃ for driving the addresser AD₆₃ is self-held by the loop of an OR circuit OR₆₂ and an AND circuit AND₆₄ under the similar conditions for the self-holding of the flip-flop FF₆₂.

The addresser AD₆₃ for addressing the third waveshape memory WM₆₃ is supplied with a drive signal when the AND condition of AND circuit AND₆₅ is satisfied. One input of the AND circuit AND₆₅ is the output of the self-holding flip-flop FF₆₃, and the other is a decay instruction signal DY which is formed in the following manner.

There are three kinds of decay instruction signal DY. Firstly, when a key is being depressed and when a key depression signal A (FIG. 2a) is generated, the AND condition of and AND circuit AND₆₆ is satisfied by a clock signal φ_(L) of a comparatively long period of clock synchronization. In consequence, the addresser AD₆₃ addresses the third waveshape memory WM₆₃ at a comparatively slow speed corresponding to the clock signal φ_(L). Accordingly, the decay envelope waveshape which is comparatively gentle is multiplied with the waveshape which is read out from the second waveshape memory WM₆₂ in a multiplier unit MU₆₀. The resultant waveshape is supplied through an adder SM₆₀.

Secondly, when the key is not depressed and the inverter key depression signal A (FIG. 2b) is generated and when the damper pedal is depressed and the pedal switch DP is opened, the AND condition of an AND circuit AND₆₈ is satisfied, and the comparatively gentle decay envelope is given to the musical sound by the same clock signal φ_(L) as in the first case.

Thirdly, when an output of an inverter INV₆₁ becomes "1" upon the release of the damper pedal to close the pedal switch DP and when the key is not depressed and the inverted key depression signal A is generated, the AND condition of an AND circuit AND₆₇ is satisfied, and a clock signal φ_(H) of a comparatively short period is transferred through an OR circuit OR₆₃ to the addresser AD₆₃. In consequence, the addresser AD₆₃ addresses the third waveshape memory WM₆₃ at a comparatively high speed. Accordingly, a rapidly decaying envelope waveshape is given in the multiplier unit MU₆₀ to the waveshape which is read out from the second waveshape memory WM₆₂. Thus, succeeding to the read-out output of the first waveshape memory WM₆₁, the above-described waveshape is delivered from the adder SM₆₀. Here, the third addresser AD₆₃ is cleared by either one of the key depression pulse KD and the key release pulse KR supplied through an OR circuit OR₆₄ as in the first embodiment.

As will be understood from the above, according to the second embodiment, the whole waveshape of the attack part is read out from the first waveshape memory WM₆₁ immediately after the depression of the key. Following the reading-out of the waveshape in the attack part, the second waveshape memory WM₆₂ is repeatedly read out. To these repeatedly read-out waveshapes, (a) the gentle decay envelope is multiplied irrespective of the depression or release of the key if the damper switch DP is opened or (b) the rapid decay envelope is multiplied immediately after the release of the key when the damper switch DP is closed.

Embodiment 3

FIG. 7 shows a third embodiment of the present invention in which a tone waveshape is caused to decay off without using a damper pedal. As can be seen in the figure, this embodiment may be regarded as a modification of the second embodiment.

This embodiment comprises three kinds of waveshape memories WM₇₁, WM₇₂ and WM₇₃ which are respectively addressed by addressers AD₇₁, AD₇₂ and AD₇₃. The first waveshape memory WM₇₁ stores the complete waveshape in the attack period, the second waveshape memory WM₇₂ stores at least one period of the tone waveshape, and the third waveshape memory WM₇₃ stores an envelope waveshape from the sustain to the decay, which envelope shape follows the attack. Therefore, after reading out the first waveshape memory WM₇₁, the second waveshape memory WM₇₂ is subsequently read out repeatedly, and the envelope waveshape which is read out from the third waveshape memory WM₇₃ in correspondence with the release of the key is multiplied in a multiplier unit MU₇₀ to the output of the second waveshape memory WM₇₂. Thus, a musical sound signal is provided from an adder SM₇₀.

Now, the construction and the operation of this embodiment will be made apparent through the following description of the processes for forming a musical tone. The arrangement of a flip-flop FF₇₁, and AND circuit AND₇₁ and an addresser AD₇₁ for addressing sampling values in the waveshape memory WM₆₁ upon arrival of a key depression pulse KD is similar to those in the first and second embodiments. The final bit output signal of the addresser AD₇₁ is used as the re-set signal for the flip-flop FF₇₁ and also as the start signal 1MF for the addresser AD₇₂ which addresses the second waveshape memory WM₇₂. These points are similar to those in the second embodiment, and will be apparent without further description.

In performing the reading-out of the second waveshape memory WM₇₂, a D-type flip-flop FF₇₂ is set through an OR circuit OR₇₁ by the signal 1MF, and the output of the flip-flop FF₇₂ is self-held when the AND condition for an AND circuit AND₇₂ is satisfied. The addresser AD₇₂ is driven through an AND circuit AND₇₃ by clock pulses φ of a predetermined period to read out the content of the second waveshape memory WM₇₂. Here, as is the case with the AND circuit AND₆₂ of the second embodiment, the inputs of the AND circuit AND₇₂ are formed with the inverted key depression pulse KD and the inverted output DF of the final bit output DF of the addresser AD₇₃ as is obtained by an inverted INV₇₀.

The reading-out of the third waveshape memory WM₇₃ is performed in the following manner. Namely, a D-type flip-flop FF₇₃ is set through an OR circuit OR₇₂ by a key release pulse KR. The output of the flip-flop FF₇₃ is self-held when the AND condition for an AND circuit AND₇₄ is satisfied. A clock signal CK₇₀ drives the addresser AD₇₃ through an AND circuit AND₇₅. Namely, when the key is released, a key release pulse KR is generated and it sets the flip-flop FF₇₃ through an OR circuit OR₇₂. Since the input conditions of the AND circuit AND₇₄ are similar to those for the AND circuit AND₇₂ associated with the second waveshape memory WM₇₂, the output of the flip-flop FF₇₃ is self-held. Thus, as one input of the AND circuit AND₇₅ continuously receives a "1" signal, the AND condition for the AND circuit AND₇₅ is satisfied when the other input receives the clock signal CK₇₀. The addresser AD₇₃ performs addressing at the period determined by the clock signal CK₇₀, and the content of the waveshape memory WM₇₃ is read out. As will be understood from the above, the clock signal CK₇₀ determines the decay speed and it may be arranged to be arbitrarily selectable. When the addresser AD₇₃ provides the last bit output, the decay is terminated. The final bit output is inverted in the inverter INV₇₀ to form the decay-termination instruction signal DF. The decay-termination instruction signal DF supplies "0" to each one input of the AND circuits AND₇₂ and AND₇₄. Therefore, the AND circuits AND₇₂ and AND₇₄ lose the AND condition and hence the inputs of the second and third addressers AD₇₂ and AD₇₃ disappear. Consequently, the reading-out of the second and the third waveshape memories WM₇₂ and WM₇₃ is terminated.

In summary, according to the third embodiment, the complete waveshape in the attack period is read out from the first waveshape memory WM₇₁ and is outputted through the adder SM₇₀ immediately after the depression of the key, and subsequently, the content of the second waveshape memory WM₇₂ storing the tone waveshape devoid of the envelope shaping is repeatedly read out to form the sustain part of the tone. Without the key releasing operation, the output of the second waveshape memory WM₇₂ continues to be delivered through the multiplier unit MU₇₀ and the adder SM₇₀. When the key release pulse KR is generated by the key releasing operation, the decaying envelope which is stored in and read out from the third waveshape memory WM₇₃ is multiplied in the multiplier unit MU₇₀ to the waveshape which is read out from the second waveshape memory WM₇₂. Thus, the musical sound is allowed to decay and extinguish.

In this manner, according to the third embodiment, the attack waveshape is formed by the use of the first waveshape memory WM₇₁, the sustain waveshape by the second waveshape memory WM₇₂, and the decay waveshape by the combination of the second and third waveshape memories WM₇₂ and WM₇₃.

Embodiment 4

FIG. 8 shows a fourth embodiment of the present invention in which the complete waveshapes in the attack and the decay of a musical sound are read out from waveshape memories.

This embodiment also utilize three waveshape memories WM₈₁, WM₈₂ and WM₈₃ which are respectively addressed by addressers AD₈₁, AD₈₂ and AD₈₃. The first waveshape memory WM₈₁ stores the complete waveshape in the attack of the tone, the second waveshape memory WM₈₂ stores a tone waveshape corresponding to one fundamental period or integer times thereof, and the third waveshape memory WM₈₃ stores the complete waveshape in the decay period of the tone. Therefore, subsequent to the reading-out of the attack waveshape from the first waveshape memory WM₈₁, the sustain waveshape is repeatedly read out from the second waveshape memory WM₈₂ in conformity with the continuation of the sustain. Subsequent to the termination of the reading-out of the second waveshape memory WM₈₂, the decaying waveshape is read out from the third waveshape memory WM₈₃. Thus, a musical tone signal if suitably generated through an adder SM₈₀.

Now, description will be made with respect to the processes for forming a musical tone signal while clarifying the construction and the operation of the arrangement.

The arrangement of a flip-flop FF₈₁, and AND circuit AND₈₁ and the addresser AD₈₁ addresses the first waveshape memory WM₈₁ upon arrival of the key depression pulse KD. The final bit output signal of the addresser AD₈₁ serves as the re-set signal for the flip-flop FF₈₁ and also as the start signal of the addresser AD₈₂ addressing the second waveshape memory WM₈₂. These points are similar to those described in the second and third embodiments, and they are not repeatedly explained here.

When the reading-out of the complete waveshape in the attack period from the first waveshape memory WM₈₁ terminates, a D-type flip-flop FF₈₂ is set through an OR circuit OR₈₁ by the signal 1MF, and the output of the flip-flop FF₈₂ is self-held when the AND condition for an AND circuit AND₈₂ is satisfied. The addresser AD₈₃ is driven by clock pulses φ of a predetermined period through an AND circuit AND₈₃ to read out the content of the waveshape memory WM₈₂. Here, as are the case with the AND circuits AND₆₂ and AND₇₂ of the second and third embodiments, the input signals of the AND circuit AND₈₂ comprise the inverted key depression pulse KD and the inverted output DF of the final bit output DF of the third addresser AD₈₃ formed by an inverter INV₈₂. The output of an AND circuit AND₈₄ is used as an input of the AND circuit AND₈₂. Inputs of the AND circuit AND₈₄ comprise a Q output of the flip-flop FF₈₂ and an output of an inverter INV₈₁. As will be described later, the output of an inverter INV₈₁ is "1" under the depression of the key. Therefore, if the Q output of the flip-flop FF₈₂ is provided, the AND condition for the AND circuit AND₈₄ and accordingly the AND circuit AND₈₂ is satisfied.

In this manner, the reading-out of the second waveshape memory WM₈₂ is performed. The reading-out is repeated until the key is released. In order to read out the second waveshape memory WM₈₂, the addresser AD₈₂ transmits a final bit output signal 2MF to an AND circuit AND₈₆ at every cycle of addressing. As will be described below, insofar as the key releasing operation is not conducted, the AND condition for the AND circuit AND₈₆ is not satisfied.

Next, when a key release pulse KR is generated in correspondence with a key releasing operation, a D-type flip-flop FF₈₃ is set through an OR circuit OR₈₂, and the output of the flip-flop FF₈₃ is self-held when the AND condition for an AND circuit AND₈₅ is satisfied. The AND circuit AND₈₅ has input signals similar to those of the AND circuit AND₈₂. Thus, one input of the AND circuit AND₈₆ becomes "1". When the signal 2MK which is the other input of the AND circuit AND₈₆ arrives, the AND condition for the AND circuit AND₈₆ is satisfied. Consequently, the AND circuit AND₈₆ provides an output, which sets a D-type flip-flop FF₈₄ through an OR circuit OR₈₃. The set output of the flip-flop FF₈₄ forms one of the input signals of an AND circuit AND₈₇ which has input signals similar to those of the AND circuit AND₈₅. The AND circuit AND₈₇ and an OR circuit OR₈₃ form a loop with the flip-flop FF₈₄ to self-hold the flip-flop FF₈₄. On the other hand, the set output of the flip-flop FF₈₄ changes one of the input conditions of the AND circuit AND₈₄ to "0" through the inverter INV₈₁. Therefore, the AND condition for the AND circuit AND₈₄ and accordingly the AND circuit AND₈₂ is destroyed. The self-holding of the flip-flop FF₈₂ is released and the reading-out of the second waveshape memory WM₈₂ is stopped. As will be apparent from the above explanation, there may be a possibility that the reading-out of the second waveshape memory WM₈₂ continues for some period after the generation of the key release pulse KR (although such time period is of no problem in the auditory sense of the tone). This is attributed to the fact that, in general, the generation of the key release pulse KR and the generation of the final bit output signal 2MF of the addresser AD₈₂ are not simultaneous. Moreover, the output of the second waveshape memory WM₈₂ and that of the third waveshape memory WM₈₃ need be continuous. It is therefore intended to address the third waveshape memory WM₈₃ after the second waveshape memory WM₈₂ has been infallibly addressed to the last.

The Q output of the flip-flop FF₈₄ as has served to stop the readout of the second waveshape memory WM₈₂ drives the addresser AD₈₃ through an AND circuit AND₈₈ by the clock pulses of the predetermined period. Then, the content of the third waveshape memory WM₈₃ is read out. It has been previously stated that the third waveshape memory WM₈₃ stores the complete waveshape in the decay period of the tone instead of only a decaying envelope shape. Upon termination of the reading-out from the third waveshape memory WM₈₃, the inverted output DF of the final bit output of the addresser AD₈₃ is generated. Therefore, each one input of the AND circuits AND₈₂, AND₈₅ and AND₈₇ becomes "0" without fail, and the flip-flop FF₈₂, FF₈₃ and FF₈₄ become ready for the next key depression.

According to the fourth embodiment described above, the complete waveshape in the attack is read out from the first waveshape memory WM₈₁ and is outputted through the adder SM₈₀ immediately after the depression of the key. The tone waveshape in the sustain is subsequently read out and outputted from the second waveshape memory WM₈₂ through the adder SM₈₀ by the signal which is indicative of the read-out termination of the first waveshape memory WM₈₁, and lastly, at the occurence of the key release, the reading-out of the second waveshape memory WM₈₂ is stopped at the next occurrence of the final address, and the complete waveshape in the decay is read out from the third waveshape memory WM₈₃ and is outputted through the adder SM₈₀, thereby completing the formation of the entire tone signal.

Modification

In the embodiments described above, the touch response of the keying operation is not taken into consideration, and a musical tone which varies according to the strength of the key depression, etc, cannot be produced. FIG. 9 shows a modified embodiment which takes this point into account. Adaptation of this modification to the attack waveshape which forms a part of each of the foregoing embodiments enables variations in the musical tone in conformity with the key operation such as the key depression speed or its pressure. The operation and the construction of this modification will be described hereinbelow.

The key depression pulse KD is generated by manipulating a key switch KSW'. A flip-flop FF₉₀ is set by the pulse to provide a Q output. The Q output enables AND₉₀ to pass clock pulses φ of a fixed period to an addresser AD₉₀. These points are similar to those in the addressing of the first waveshape memory in each of the foregoing embodiments.

According to this modification, however, the depressed state of the key switch KSW' is sensed by a sensor SE and converted to an electric signal. The peak value of the key depression strength is held by a holding circuit HL, whereupon the held value is converted to a digital value by an A-D converter ADC. The converted digital value is a read-out signal for a decoder DE. Depending upon the value, the decoder DE generates an "enable" signal EN which instructs one of a plurality of waveshape memories WM₉₁ -WM_(9N) to be read out. The waveshape memory which is selected and supplied with the "enable" signal EN from the decoder DE stores a complete waveshape in the attack, in conformity with the particular key touch. Such a selected complete waveshape is read out by the addresser AD₉₀.

Here, the sensor SE may be formed of any one of the various known types. For example, an electrically conductive material whose resistance value varies with the strength of the key depression may be combined with the key. Regarding the holding circuit HL, any one of a variety of known sample and hold circuits can be employed.

According to the present invention, at least one of the waveshape memories is arranged to store the complete waveshape of at least part of a musical tone as described above, whereby an electronic musical instrument can easily simulate various natural sounds and generate various artifical sounds as musical sounds. 

We claim:
 1. An electronic musical instrument of a waveshape memory reading type comprising:keyboard means comprising a plurality of keys for producing key depression signals in response to an operation of each key, each said key designating a musical sound; means for sensing depression state values for each said key, said depression state values being parameters from the group consisting of key depression speed and key depression pressure; a plurality of waveshape memories of a random access addressed type, each for storing amplitude sample values for a waveshape at respective addresses of the memory, the waveshapes stored in said memories being different from one memory to others; an addresser, connected to said waveshapes memories and to said keyboard means, for addressing said waveshape memories at a speed determined in response to said key depression signals to produce a tone signal representing a designated musical sound; and means for selecting different predetermined ones of said waveshape memories based on a detected value of said depression state value, thereby producing musical sounds which vary in response to said depression state value.
 2. A musical instrument as in claim 1 wherein said waveshape memories store amplitude sample values of a waveshape that include plural cycles of vibration which constitute only an attack portion of a sound exhibiting sound factors which vary with time.
 3. An electronic musical instrument of a waveshape memory reading type comprising:keyboard means including a plurality of keys, each of which designates a musical sound, for producing key depression and release signals in response to an operation of each said key; a waveshape memory of a random access addressed type, for storing amplitude sample values of a waveshape at respective addresses of the memory, said waveshape memory storing a frist waveshape which includes a plurality of cycles of vibration, each cycle having its own shape independent of other cycles and which exhibits a predetermined characteristic defining a musical tone frequency when read out at a speed, said plurality of cycles being sufficient for defining an attack portion of a tone, said waveshape memory further storing a second waveshape which includes at least one cycle of vibration defining a sustain portion of a tone when read out repeatedly; an addresser connected to said waveshape memory and to said keyboard means for addressing said waveshape memory at a speed determined in response to said key depression signals, to produce an attack portion of a tone and subsequently thereto a sustain portion of said tone; and envelope imparting means connected to said waveshape memory and to said keyboard means for imparting a decay envelope to the tone produced from said waveshape memory upon receipt of said key release signal.
 4. An electronic musical instrument according to claim 3, further comprising a damper switch connected to said envelope imparting means for controlling said envelope imparting means, to impart a gradual decay envelope to the tone produced from said waveshape memory upon receipt of said key release signal when said damper switch is not actuated, and to impart a quick decay envelope to the tone produced from said waveshape memory upon receipt of said key release signal when said damper switch is actuated.
 5. An instrument as in claim 3, wherein said predetermined characteristic is one of (a) pitch and (b) frequency.
 6. An electronic musical instrument of a waveshape memory reading type comprising:keyboard means, including a plurality of keys, each of which designates a musical sound, for producing key depression and release signals in response to an operation of each said key; a waveshape memory of a random-access addressed type, for storing amplitude sample values at respective addresses of the memory, said waveshape memory storing a waveshape of a tone from its attack portion to its decay portion; an addresser connected to said waveshape memory and to said producing means for addressing the waveshape memory at a speed determined in response to the key depression signals, thereby producing a tone signal representing the designated musical sound; and envelope imparting means connected to said waveshape memory and said keyboard means for imparting a decay envelope to the tone produced from said waveshape memory upon receipt of said key release signal.
 7. An electronic musical instrument according to claim 6, further comprising a damper switch connected to said envelope imparting means for controlling said envelope imparting means to impart a gradual decay envelope to the tone produced from said waveshape memory upon receipt of said key release signal when said damper switch is not actuated, and to impart a quick decay envelope to the tone produced from said waveshape memory upon receipt of said key release signal when said damper switch is actuated. 